The invention relates in general to Virtual Private Networks (VPN). In particular the invention relates to managing VPNs.
Public networks are presently being used more and more for sensitive and mission critical communications and the internal networks of various organisations and enterprises are nowadays connected to the public networks, Internet being one of them. Since the basic mechanisms of the public networks were originally not designed with secrecy and confidentiality in mind, public networks are untrusted networks.
Virtual Private Networks (VPN) are commonly used for connecting trusted parties to each other over untrusted public network through a secure tunnel. All traffic from a first party to a second party is encrypted in a security gateway of the first party, sent in encrypted form over the public network to the second party, where the transmitted data is decrypted in a security gateway and the decrypted data is forwarded to the recipient. The VPN is typically transparent to the processes that are communicating between each other and the encryption and decryption depend on the configuration of the VPN between the parties. However, the security gateways need to have information about the configuration of the other end of the VPN in order to be able to encrypt and decrypt the traffic correctly. The configuration includes things like addressing, encryption algorithm and key information of the other end security gateway. The configuration information is usually conveyed between the administrators of different sites by means of phone or some other traditional communication system. The administrators then input the configuration to the security gateways of their sites in order to enable VPN connections between the sites. The actual encryption keys are exchanged in VPN communication, but the configuration that is needed for initiating VPN connection needs to be conveyed by some other means.
Large VPNs are complicated and tedious to manage. Keeping the information about the structure of the VPN up to date at each site (network or group of networks connected to the VPN) is problematic but mandatory. Every site must have the correct configuration for all the other sites in order to communicate with them. In large VPNs there may be dozens or hundreds of sites and the configuration may vary in time rather frequently, and if the configuration of one VPN site changes all sites need to be updated. That is, the administrator of the sites changing its configuration needs to contact administrators of all other sites and communicate the changes to them, whereby they need to re-configure their security gateways.
FIG. 1 illustrates an example network topology with four sites 101-104, who are able to communicate with each other by means of VPNs. The sites 101-104 are connected to the Internet 100 via security gateways 105-108. Each security gateway is managed via a site-specific management server 109-112, which usually resides inside respective site and to each site there is configured VPN configuration information of all other sites as well as the configuration of the site itself. In case the security gateway functions as a firewall; the firewall configuration (access rules) of the security gateways is naturally not duplicated to the other sites.
One proposal for managing large VPNs is a star like VPN, where a central “hub” acts as a VPN router. Each site connects to the hub, which decrypts the packets and then re-encrypts them for the connection from the hub to the target site. This way, the VPN sites do not need to have up-to-date VPN information of all other sites; instead it is enough to be able to connect to the central hub.
FIG. 2 illustrates the network topology of FIG. 1 in connection with the star like VPN. The sites include now only VPN configuration of the site itself and of a central hub 200. The central hub includes VPN configuration of all the sites in the configuration, and the sites connect to each other via the central hub.
The disadvantage of the star like VPN is that vast amounts of processing power are required at the hub. The security gateway at each site still has the same amount of encryption load as in a standard distributed VPN, but the hub's load is in fact equal to the sum of the loads of all the sites. In large-scale VPNs this may be difficult or impossible to achieve and in any case very expensive. Furthermore, the data transmitted in the VPNs is in cleartext form within the hub, which is clearly a security risk.
If all the sites belonging to a VPN belong to the same organization, it is possible to administer them centrally by means of existing tools. In this case, all aspects of the security gateways, including access control configuration, are managed from one central point. However, the sites joining a VPN are not always sites of one party, but many different organizations may wish to establish a VPN between them. Clearly, such central management of all aspects of security gateways is not suitable, if different organizations are involved. Therefore a new way to manage VPNs of more than one organisation and especially large VPNs is required.